1.6 and aaz valve diameters

[theman53]

1.6 is 34mm in 31mm ex
1.9 is 36mm in 31mm ex
Tdi is same as aaz but slightly different lengths

I robbed this from a post. Don't know if it is 100% accurate, but I wanted to be able to find this next time around. I think this is the main reason the aaz head is the upgrade to the 1.6...time will tell.

[R.O.R-2.0]

port shape is also much better on the AAZ.

[rallydiesel]

And later AAZ and all tdi have 7mm stems as opposed to 8mm.

[theman53]

port shape is also much better on the AAZ.

So I hear people say, but I really think the oval will flow better than the D. The D might have less turbulance or less tumble, but until my next project I won't know for sure.

[R.O.R-2.0]

port shape is also much better on the AAZ.

So I hear people say, but I really think the oval will flow better than the D. The D might have less turbulance or less tumble, but until my next project I won't know for sure.

i would think the D port would flow better, because its bigger..

bigger ports usually flow better..

[theman53]

port shape is also much better on the AAZ.

So I hear people say, but I really think the oval will flow better than the D. The D might have less turbulance or less tumble, but until my next project I won't know for sure.

i would think the D port would flow better, because its bigger..

bigger ports usually flow better..

Agreed somewhat. The my 1.6 head intake port measures 1-3/8 tall x 1-1/8 wide oval. My AAZ head intake port measures 1-7/16 tall x 1-1/16 wide. I really think the valve is the big difference in flow. The shape is probably to reduce tumble/turbulation, which should help performance. I want to do both a 1.6 and 1.9 head and see what actually does better at a HG change....horribly off the topic here, sorry. If I go further I will split the thread.

[erice1984]

1.6 is 34mm in 31mm ex
1.9 is 36mm in 31mm ex
Tdi is same as aaz but slightly different lengths

I robbed this from a post. Don't know if it is 100% accurate, but I wanted to be able to find this next time around. I think this is the main reason the aaz head is the upgrade to the 1.6...time will tell.

I can vouch for the 1.9 and 1.6 Exhaust valves being the same diameter, I ordered them that way for my AAZ head.
The Intake valves are different, AAZ larger, 1.6 smaller.